1. Field of the Invention
This invention relates to a method and apparatus for venting containers housing energetic materials. In particular, the invention relates to an impact initiated venting system and a method of using same.
2. Description of Related Art
Energetic materials, such as explosives and propellants, are often found in confined spaces within munitions. Under normal conditions, these materials are unlikely to explode or burn spontaneously; however, many are sensitive to heat and mechanical shock. For example, when exposed to extreme heat (as from a fire) or when impacted by bullets or fragments from other munitions, the energetic materials may be initiated, causing the munitions in which they are disposed to inadvertently explode prematurely.
Efforts have been made to develop “insensitive munitions,” which are munitions that are generally less likely to detonate except in their intended missions to destroy targets. It is less likely that such an insensitive munition will detonate if a bullet or a fragment from an explosion strikes it. Moreover, it is less likely that such an insensitive munition will detonate if it is in close proximity to a target that is hit. Similarly, if the insensitive munition is exposed to extreme temperatures, as from a fire, the insensitive munition will likely only burn, rather than explode.
One way that munitions have been made more insensitive is by developing new explosives and propellants that are less likely to be initiated by heating and/or inadvertent impact. Such materials, however, are typically less energetic and, thus, may be less capable of performing their intended task. For example, a less energetic explosive may be less capable of destroying a desired target than a more energetic explosive. As another example, a less energetic propellant may produce less thrust than a more energetic propellant, thus reducing the speed and/or the range of the munition. Additionally, the cost to verify and/or qualify new explosives and/or propellants, from inception through arena and system-level testing, can be substantial when compared to improving the insensitive munition compliance of existing explosives and/or propellants.
Another system has been developed that selectively vents a container in which an energetic material is disposed, such as a munition, at a predetermined temperature or within a predetermined range of temperatures. In one particular embodiment, a pyrotechnic train is initiated at a particular temperature or within a particular range of temperatures that, in turn, detonates a cutting charge, such as a linear shaped charge. The explosive products from the cutting charge are used to cut the container, thus releasing pressure therein or preventing the buildup of pressure therein. The impact of a bullet, fragment, or shaped charge jet with the container proximate the venting system may result in a temperature sufficient to initiate the venting system. Additional safeguards, however, may be desirable to ensure such a venting system is initiated in the event of an impact to the container.
While there are many ways known in the art to render munitions more insensitive, considerable room for improvement remains. The present invention is directed to overcoming, or at least reducing, the effects of one or more of the problems set forth above.